Manufacture of acetylene



y 1944- J. D. RUYS ET AL MANUFACTURE OF ACETYLENE Filed March 14, 1941 Gas Inlet amlfold Per'for'azed Pzkoe 2 Casing crap er Recs 51/029 Hopper Wafer Mie z'sc/zarye Pzpe FigJI \nvenfors: Jan D. Ru ys Leonard Goldmein g 2 A By his Afiorney:

Patented May 16, 1944 MANUFACTURE OF ACETYLENE Jan D. Buys, Pittsburg, and Leonard Goldstein, Concord, Calih, assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application March 14, 1941, Serial No. 383,384

Claims.

This invention relates to the production of hydrocarbons having a high carbon content from bydrocarbons having a low carbon content, and more particularly pertains to the production of acetylene from hydrocarbons, such as paiaflln hydrocarbons, olefin hydrocarbons, aromatic hydrocarbons, naphthenes, natural gas which contains a preponderance of methane, casinghead gas vapors, industrial gases containing hydrocarbons, and the like. In one of its Specific embodiments the invention includes a novel process and apparatus for the economical, technical-scale manufacture of acetylene from the above-mentioned hydrocarbons, and particularly from gases preponderating or rich in methane.

It is known that acetylene may be produced by subjecting the hydrocarbons and their mixtures, e. g., methane-rich natural gas, to an incomplete combustion with oxygen, air or an oxygen-containing gas, at or above the ignition temperature of the gaseous mixture and under conditions whereby flame combustion is maintained. In order to improve the yield of acetylene it has been proposed to regulate the hydrocarbon-oxygen ratio and to effect the incomplete combustion in an enclosed combustion zone while maintaining the linear gas velocity essentially above the respective flame velocity of the gaseous mixture in the combustion zone. This process is disclosed and claimed in U. S. Patent 1,965,770. Be cause of the gas velocities employed in the process, the flame tends to' tear itself away from the,

mouth of the burner and thus become extinguished. The patent describes various methods and means which may be employed for maintaining flame combustion in the reaction zone. For example, such flame combustion may be maintained, in spite of the high velocity of the gas mixture introduced into the reaction zone through the main burner or burners, by providing additional gas inlets or nozzles through which a combustible gaseous mixture emerges at a velocity below the respective flame velocity of the gas, these pilot flames sustaining flame combustion of the main stream of gases in the reaction zone. In the alternative, it is possible to sustain flame combustion by heat applied externally or internally to the reaction vessel or to some portion or portions thereof.

A modification of the above-outlined process is disclosed and claimed in U. S. Patent 1,965,771. According to this patent high yields of acetylene may be obtained from gaseous mixtures possessing an initial gas velocity which need not be greater than the respective flame velocity. This is. accomplished by providing a comparatively small section of flame at the base (i. e. near the outlet from the burner proper) in which section the gas velocity does not exceed the flame velocity, while in the remaining portion or section of the reaction zone the gas velocity is essentially higher than the flame velocity of the gaseous mixture. The section near the burner allows the maintenance of a flame although the main portion of the combustion takes place in the section in which the gas velocity is essentially higher than the respective flame velocity of the mixture. These results may be attained by employing difierent methods or means which are described in extenso in the aforementioned patent-U. S. 1,965,- 771. For instance, the reaction chamber may consist of two sections: a relatively wide section containing the burner through which the gaseous mixture to be treated is introduced, and a relatively narrow section. In the wider section the gas velocities are not greater than the respective flame velocity. This allows the maintenance of flame combustion. The flame thus maintained then passes into the narrow channel, tube, slot or the like, in which the gas velocity (because of the constricted cross-sectional area) exceeds the flame velocity of the gaseous mixture, the flame being drawn out in the constricted portion to a long and narrow needle or sheet-like tip. The

maintenance of flame combustion may also be promoted by the use of baflles in the burner face, these bailles creating dead spaces or local retarding effects which may or may not be created by eddies resulting from the positioning of the bailles in the path of the gas stream.

The use of the above-outlined process results in the production of relatively high yields of acetylene. However, certain technical difflculties render it uneconomical to employ the structures disclosed in the U. S. Patent 1,965,771 for the commercial manufacture of acetylene. When employing tubular or channel type structures for the construction of the reaction chamber, and particularly those in which a part of the combustion occurs in a narrow section in which the gas velocity of the-flame is greater than the respective flame velocity, it is generally diflicult to maintain high acetylene yields because they are greatly affected by even relatively small changes in the various operating conditions. For example, it was found that the yield of acetylene, other conditions being maintained equal,-will vary greatly by even small changes in the distance between the burner face and the constriction, i. e. the distance to the point at which the flame is conflned to a small volume by the diminished cross-sectional area of the narrow part of the reaction zone. Also, the width of the baiile in the burner faces of the structures disclosed in U. 8. Patent 1,965,771 is quite critical, and a change therein markedly affects the yield of acetylene. Furthermore, it is known that carbon is a by-product of acetylene manufacture, and that a part of this carbon is deposited on the inner walls of the reaction zone and particularly in the restricted portion thereof. The carbon must be continuously or at least intermittently removed from these walls because an accumulation of the carbon, besides retarding the removal of the heat of combustion, also gradually plugs up the reaction zone thus preventing continuous operations. when using relatively long and narrow constricted reaction zones (whether in the form of channels or tubes), the scraping of the carbon from the inner walls of such reaction chambers is very diflicult, if not practically impossible, particularly due to the excessive warping and distortion of the reaction walls due to the wide diflerences in the temperatures of the various parts of the structure.

It is therefore an object of this invention to 3 avoid the above and other defects, and to provide an improved process and apparatus whereby high yields of acetylene may be. commercially and economically produced by the incomplete combustion of gaseous mixtures according to the principles disclosed and covered by the abovediscussed patents. It is a further object to provide a process and means whereby high yields of acetylene may be produced continuously and on a commercial scale. Additional objects will become apparent as the invention is described in detail hereinafter.

It has been found that the foregoing and other objects may be attained by forming a gaseous mixture containing hydrocarbon and oxygen, introducing this mixture into a reaction zone under conditions whereby flame combustion therein may be maintained, conveying this gaseous mixture (while in a state of flame combustion) through the locus of minimum clearance between the surfaces of two revolving metallic cylinders having a relatively small clearance thereinbetween, rotating said cylinders so that the tops thereof move inwardly toward said locus of minimum clearance, cooling the surfaces of the rotating cylinders thereby extracting a portion of the heat of combustion and preventing excessive decomposition of the acetylene formed as a result of this flame combustion, and recovering the acetylene from the resulting reaction products after the passage thereof through the aforementioned locus of minimum clearance between the relatively cooler surfaces of the rotating cylinders.

When the flame combustion of the gaseous mixture is effected under the above conditions, the gaseous mixture entering the reaction zone through the burner nozzle is initially preferably traveling at a rate which is not greater than decreasing area. This is due to the fact that the gas stream, being directed towards the locus of minimum clearance or separation between the mentioned rotating cylinders, is impinged by the walls or surfaces thereof. The velocity of the gas stream, therefore, increases as it approaches the locus of minimum clearance. However. due

the respective flame velocity. There is thus no 7 to the chemical reactions occurring during the combustion and because of the gradual cooling of these gases by the relatively cooler surfaces of the cylinders, the gas velocity is not proportional to the differences in the cross-sectional areas at the various points in the reaction zone between the burner face and the aforementioned locus of minimum clearance or separation between the rotating drums or cylinders. vNevertheless, it is believed that the velocity of the gaseous mixture at the above locus is definitely above the respective flame velocity of the gaseous mixture. In this connection it must be noted that there are at least two theories as to the reason why the use of restricted sections in which the flame is confined to a smaller volume is beneficial for the production of high yields of acetylene. According to the theory discussed in the aforementioned patents, the high yield of acetylene production is due to the use of gas velocities which are essentially greater than the respective flame velocity of the gaseous mixture. on the other hand, there is a theory that the use of the method and means described herein benefits the recovery of acetylene as distinguished from its production. According to this theory the provision of restricted cross-sectional areas permits adequate cooling of the reaction mixture so that the acetylene formed is not decomposed by further combustion to carbon. The increase in the velocity of the gaseous mixture p as it approaches the narrow portion of the reaction zone) helps heat transfer by bringing the mixture in quicker contact with the colder wall surfaces of the internally cooled rotating drums. thus also aiding the acetylene recovery. It is also possible that both of the above explanations are correct, and that the consistently high yields of acetylene are caused by the fact that the use of restricted zones in which the gas velocity is comparatively high and is equal to or preferably greater than the respective flame velocity beneflts not only the formation of the acetylene but also its recovery. In other words, it is possible that the process and apparatus of the present invention cause high conversions to acetylene and also prevent further decomposition of the acetylene thus formed, thereby permitting the recovery of high yields thereof. It is to be understood, however, that there is no intention of bang limited by any of the theories presented a ve.

To facilitate understanding of the invention and for the purpose of a more exact illustration and description thereof, reference is now made to the accompanying drawing which shows diagrammatically a preferred embodiment of a structure adapted for the production of acetylene according to this invention. In the draw ing, Figure I shows a vertical section through the preferred arrangement adapted to carry out the process, while Figure II is a section taken along line l-l of Figure I.

Referring to the drawing, the reaction apparatus disclosed therein includes a casing generically designated by the'numeral ll. Two hollow metal cylinders Ii and i2 are disposed in a substantially horizontal position within this cas- ,ing. The cylinders extend substantially the length of the casing and are disposed parallel to each other on substantially the same horizontal plane and in such a manner that there is only a relatively small clearance ll between said cylinders. Each of these cylinders is provided with pipes l4 and i5 extending outwardly along the longitudinal axis of the cylinder, these pipes pipes supporting each cylinder, these means revolving the metal cylinders in opposite directions, as shown by the arrows (Fig I), so that the top of each cylinder moves inward and downward toward the clearance opening I! between the cylinders.

The diameterof the revolving cylinders may vary within very wide limits. For example, good results have been obtained by an apparatus containing cylinders having, diameters varying between about 6 inches and about 30 inches. Cylinders having larger or smaller diameters may also be used. However. the use of very large cylinders, e. 3. having a 60-inch diameter, are uneconomical and cumbersome both from the construction and operation points of view. On the other hand, apparatus containing cylinders of a 6-inch or smaller diameter require highly controlled operating conditions, since otherwise the yields of acetylene become unsatisfactory. For instance, when using such cylinders of relatively small diameters, there is frequently a tendency for the flame to leave the burner face and to burn below the slot or clearance l3. Under such conditions the acetylene yields drop below a satisfactory minimum. As a general rule, it may be said that cylinders having a diameter of about 10 inches or more are quite satisfactory. As to the rate of rotation of these cylinders, this will also vary greatly depending on a number of factors, such as the degree of cooling of the cylinder walls, the variation in the clearance between the cylinders, their diameters, etc. A favorable speed of rotation for the cylinders is generally between about 50 and 500 R. P. M., good yields having been obtained when 14-inch cylinders were rotated at a speed of about 60 to 100 R. P. M.

The gaseous mixture to be burned in the apparatus is introduced thereinto through a manifold 22 arranged in the upper part of the casing Hi, this manifold extending along the longitudinal length of the casing'and substantially in a vertical plane through the constriction l3 between the cylinders I4 and ii. The manifold 22, as shown in the drawing, consists of a longitudinally disposed housing 23 containing a pipe 24 providedwith perforations 25. The lower side of the housing 23 is covered by a screen 26. which is separated longitudinally into two sections by a centrally disposed baffle 21. A second screen 28 is provided within the housing 22 and above communicating with the interior of the cylinder 1 assaoov v 3 screen 20, this second screen aiding in gas distribution by bringing the gas flow ginto the stream-line region before it enters into the interstices oi the lowermost screen 20. The gaseous mixture is introduced into pipe '24 through pipe III. In the preferred embodiment, manifold 22 is constructed so that it may be removed from casing III for purposes of igniting the gaseous mixture at the start of operations, the manifold being then lowered into position and locked in place by any known orsuitable means not shown in the drawing.

Scraping devices in the form of knife blades are arranged, as shown by 22 and 32, with the edges of the blades held firmly against the surfaces of the respective cylinders as they revolve, these blades being pivotally arranged on shafts 3i and :35, respectively, extending outwardly through the end walls ll and II of the casing Iii. For the purpose of a firm engagement between the scrapers 32 and II and the cylinder walls, shafts M and 35 may be provided with suitable tension means, such as a counter-weight 35. The scrapers remove the carbon and carbonaceous materials deposited on the walls of the cylinders so that the surfaces coming in contact with the burning gaseous mixture are continuously substantially clean and free from the carbonaceous material. The carbon thus scraped from the surfaces falls to the bottom of the chamber and is removed therefrom by suitable means such a those described hereinbelow. J

Below the cylinders H and I2, casing ll is provided with a hopper 38 the upper edges of which extend inwardly into the'interior of. the chamber so as to provide troughs 39 on either side of the hopper. These upper edges of the hopper are preferably serrated as shown by numeral 40. A pipe II is provided to introduce water or the like into the troughs 39, this water flowing over the serrated edges 40 of the hopper and thereinto to wash down the carbon, etc., scraped off the cylinders Ii and i2. Additional water or other washing liquid may be introduced into the lower part of. hopper 38 via pipe 42. The reaction products are removed from the system through line 43, the acetylene formed as one of the reaction products being then recovered in any known manner.

In operation, the hydrocarbon, such as methane or a methane-rich gas, and oxygen or an oxygen-containing gas are introduced into the system via pipe 30, and the mixture, after passing through the two screens 28 and 26, is ignited thus forming an inverted flame in the space en-'- closed by the screen 26 and the sides of the cylinders H and I2. The rate of flow of the gaseous mixture thus introduced may vary within rela-, tively wide limits depending on a number of factors, such as the distance between the burner face (i. e. lower screen) and the locus of mini- ,mum clearance between the cylinders, the ratio of oxygen to hydrocarbons in the gaseous mixture, diameter of cylinders, etc. Generally; however, it is advantageous to employ an initial velocity which is not greater than that of the respective flame velocity of the gaseous mixture.

Simultaneously with the initiation of combustion, the rotation of cylinders Ii and i2 is started. Also, water or a similar cooling fluid is circulated through the interior of these cylinders via pipes l4 and I5. Although there is no intention of being limited to the specificcooling means described herein nor to any specific temperature' within the cylinders, it was found that highly satisfactory results may be attained by cooling the interior of the cylinders by allowing water to be evaporated therein. For this purpose, water was continuously introduced into' each cylinder through its respective pipe ll, the steam evolved therein (caused by the heat transmitted from the reaction zone) being continuously withdrawn through the corresponding pipe ii. In one of the specific embodiments employed, this steam was condensed and the water, after further pre-cooling. was.rccycled back into the cylinders for further extraction oflieat therefrom. In this manner, the heat of the internal walls of the cylinder never rose much above 100 C.

The flame passing through the space between the screen 28 and the locus of minimum clearance (i. e. constriction l8) between the cylinders thus passes through zones or sections of gradually decreasing area. Therefore, the flame thus burns at gradually greater gas velocities which, at the aforementioned locus it, exceeds the flame velocity. Simultaneously, the. gases come in closer contact with the walls of the rotating cylinders which, because of the circulating 'fluid, are considerably cooler than the flame. The combustion gases therefore yield a considerable portion of their heat to the cylinder walls and are thus cooled to such an extent that the gases below the locus of minimum clearance are usually at a-temperature which is not greater than about 400 C. to 470 C. In fact, in many cases, this temperature is even below 400-C. This cooling of the flame prior to its passage through constriction ll prevents the decomposition of the acetylene formed during the flame combustion of the introduced gases. Thacfibon producedjuring the combustion is in part deposited on the rotating cylinders, and is scraped therefrom by the scrapers 33.

The hydrocarbon-oxygen ratio of the gaseous mixture subjected to flame combustion in accordance with the process of the present invention may vary within relatively wide limits. However, to obtain high yields of the desired acetylene the ratio of the carbon (of the hydrocarbon) to the oxygen should be maintained between about 1.4:1 and about 1.6:1, and preferably between about 1.48:1 and about 1.54:1. This ratio is based on the total carbon and not on the hydrocarbon per se because the carbon content of a hydrocarbon mixture will vary depending on the constituents thereof.

The height of the burner face above the constriction It, i. e, above the locus of minimum clearance between the rotating cylinders, is conveniently made adjustable for different gas mixtures and throughput rates. A faster gas flow or a less explosive mixture needs a larger space for the flame base, since otherwise the flame base, having too small a base, is blown out through the constriction I 3 into the unrestricted space below the cylinders, wherein further combustion to carbon and, therefore, a decrease in the acetylene yield occurs. It is to be noted. however, that this distance between the burner face and the locus of minimum clearance between the cylinders may be varied considerably without materially affecting the acetylene yield. In fact, it was found that, whereas a variation of even a few millimeters in this distance materially af- ,fected the acetylene yield when employing the structures disclosed in the aforementioned U. S. Patent 1,965,771, the yields were substantially unaflected when the burner was moved relativell ly greater distances from the locus of minimum clearance betweenthe cylinders of the present structure.

The use of a plurality of screens in the burner s manifold is advantageous in that it permits longer uninterrupted operations and more consistent yields of acetylene. This is probably due to the fact that each screen causes the gaseous mixture passing therethrough to be deflnitely'within the i stream-line region, this region being preferable both from the standpoint of yields and of inhibition of screen destructions. It is to be understo,od, however, that the invention is not to be limited't'o theuse of such multiple screens since. is under certain conditions, it is possible, and may be even advantageous, to use burners with a single screen. The presence of a bailie in the bumer face permits the use of gas velocities approaching the flame velocity, without flickering of the g0 flame, by creating an expansion space in the combustion chamber under the baille. This baffle, apparently, also serves to keep the base of the flame from getting too close to the screen and destroying the same. The shape and sizeof the bane maybe varied to obtain optimum results. -The distance between the revolving cylinders may also be changed. However, care should be-taken to prevent the use of excessive widths between the cylinders since this decreases the heat transmission to the walls thereof, as well as the desired. constriction in the width of the flame. Also, the bringing of the cylinders too close to each other may cause excessive back pressures unless a partial vacuum is employed downstream of the locus .of minimum clearance between the cylinders. With 14-inch cylinders a clearance of 1'; inch gave good results. However, larger and smaller clearances may be. used without materially aflfecting the yield of acetylene.

By way of illustration only, reference will be had to certain examples of the process of the present invention.

Example I The apparatus shown in the drawing and described hereinabove was used. The cylinders had a diameter of 14 inches and were disposed horizontally leaving a minimum clearance of about 1'; of an inch thereinbetween. These cylinders were rotated at a speed of about R. P. M. and

were cooled by passing water through the interior of these cylinders and by allowing the water to evaporate therein. The steam was continuously withdrawn, condensed, and the water thus formed was recycled back through the cylinders. The burner face (lower screen) was disposed about 5 /2 inches above the locus of minimum clearance between the cylinders. The flow of gases to the mixing nozzle (not shown) was 48.7 cubic meters per hour'of California natural gas and about 42.6 cubic meters per hour of a gas containing 84.8% oxygen and about 15.2% nitrogen. The natural gas predominated in methane but contained a small percentage of ethane and other hydrocarbons as well as about 2.8% nitrogen. The ratio of carbon-to-oxygen in the inflowing gaseous mixture was 1.52:1. The ignited mass was conveyed through the reaction chamber and the locus of minimum clearance between the cylinders, the average temperature at a point just below this locus between these cylinders being about 445 C. The walls of the rotating cylinders were maintained substantially clean by continuously scraping ofl the carbon deposited thereon. The resulting gas was continually withdrawn from the reaction zone and upon analysis showed the following composition (the percentages being calculated on a dry basis):

The exit gas, the volume of which was equal to about 98.4 cubicmeters per hour, thus contained about 6.0% acetylene, from which it may be calculated that about 21.6% of the carbon of the introduced hydrocarbons was converted to acetylene. The yield of carbon (a major portion .of which was scraped oil? the cylinders) was equal to about 4.2 lbs. per 1000 cubic feet of natural gas thus treated.

Example II This run was effected in the same apparatus as that employed for the previous experiment with the exception that the burner was lowered so that it was only 4 inches above the locus of minimum clearance between the revolving cylinders. The total gas throughput (consisting of the methane-rich gas and the oxygen-containing gas) was equal to about .73.8 cubic meters per hour, this gaseous mixture having a carbonoxygen ratio of 1.53:1. The average temperature below the locus of minimum clearance between the rotating cylinders was equal to about 400 C. The resulting gas had the following composition:

Per cent Cal-Ia 6.1 CO9 3.7 CO 25.4 We 48.0 0:! 1.0 Cal-T4 1.8 CH4 5.9 Na

Example III Per cent C 6.1 CO2 3.0 CO v 25.7 I-Ta 49.1 0 0.3 C 1.8 C 5.2 No 8.8

Example IV The apparatus employed in Examples II and m was used. The flow of gases to the manifold was 53.6 cubic meters per hour of a California natural gas predominating in methane and about 47.2 cubic meters per hour of a gas containing 83.5% oxygen and about 16.5% nitrogen. The total flow was thus equal to about 100.8 cubic meters per hour. The carbon-oxygen ratio was 1.55:1. The cylinders of the apparatus'were rotated at 60 R. P. M. and their walls were cooled by evaporation of water circulated therethrough, the temperature immediately below the cylinders being about 460 C. The resulting gas had the following composition:

' Per cent 02H: 6.0 C02 3.3 CO 26.0 Hz 49.2 02 0.2 C2H4 1.3 CH4l 6.8 N: 7.2

An analysis of the results of the last three examples shows that the rate of throughput may be varied within relatively wide limits without affecting the acetylene yield. However, when the total throughput was dropped to about 36.6 cubic meters per hour, the acetylene content of the exit gases was only 4.6%, thus indicating excessivecombustion in-the reaction zone.

From the above examples it is seen that the eilluent gas contains, in addition to acetylene, substantial quantities of carbon monoxide and hydrogen. The ratio of these two compounds is usually equal to between about 1:1.85 to about 1:1.95, thus rendering the gas valuable for the synthesis of alcohols or for the production of hydrogen.

The invention is not restricted to the use of normally gaseous hydrocarbons nor to mixtures of the same, as it can be utilized with liquid hydrocarbons which have been just vaporized by any suitable means. Also, instead or using pure oxygen, mixtures predominating in or containing large percentages of oxygen, together with other gases which may or may not be inert, e. g. nitrogen, hydrogen, etc., may also be employed. The presence of inflammable gases increases the speed or the flame propagation, while the presence of inert gas enhances the economy of the process.

The process may be conducted at atmospheric pressure, although it may also be carried out to advantage at pressures slightly above atmospheric.

Instead of employing cylindrical drums for impinging on the gaseous mixture subjected to incomplete combustion according to the present invention, it ispossible to use conical containers, truncated cones and other cylindrical drums. which will be arranged to impinge on the flame and provide a locus of minimum clearance through which the gaseous mixture must pass before leaving the reaction zone. Also, instead of arranging the rotating cylinders in the preferred horizontal plane, these rotating drums may be disposed along other planes provided that the axes of the drums are substantially parallel thereby forming a locus of minimum clearance therebetween.

We claim as our invention:

1. A method for producing acetylene which comprises forming a, gaseous mixture containing a methane-rich hydrocarbon and oxygen in a carbon (in the hydrocarbon) to oxygen ratio of between about 1.4:1 and about 1.621, introducing said gaseous mixture into a reaction zone at an initial linear gas velocity not greater than the flame velocity of the gaseous mixture, subjecting said mixture to flame combustion in said zone, conveying said ignited gaseous mixture in said reaction zone downwardly towards and through the locus of minimum clearance between the surfaces of two metallic cylinders revolving on sub-- bustion taking place in a vertical plane located substantially midway between the axes of said cylinders, rotating said cylinders so that the tops thereof move inward toward said locus of minimum clearance, cooling thesurfaces of said rotating cylinders thereby extracting at least a portion of the heat from the gaseous mixture subjected to flame combustion and maintaining the resulting gaseous mixture downstream of said locus at a temperature below that of flame combustion, withdrawing the resulting gaseous products from a zone below said locus of minimum clearance, and recovering acetylene from said gaseous products.

2. The method according to claim 1 wherein the linear gas velocity of the gaseous mixture while passing through the locus of minimum clearance between the revolving cylinders is maintained substantially above the respective flame velocity of the gaseous mixture.

3. A method for producing acetylene which comprises introducing a gaseous mixture containlng a hydrocarbon and oxygen into a reaction zone at an initial linear gas velocity not greater than the flame velocity of the gaseous mixture, subjecting the mixture to flame combustion in said zone, conveying said ignited gaseous mixture downwardl towards and through the locus of minimum clearance between the surfaces of two metallic cylinders revolving on substantially horizontal axes and with a relatively small clearance therebetween, said flame combustion taking place in a verticalplane located in said locus of minimum clearance, rotating said cylinders so that the tops thereof move inward towards the locus of minimum clearance, conveying a cooling medium through the interior of each of said rotating cylinders thereby extracting at least a portion of the heat from the gaseous mixture subjected to flame combustion, passing the gaseous mixture through the locus of minimum clearance between said cylinders at a linear velocity substantially above the respective flame velocity, withdrawing the resulting gaseous products from a zone below said locus of minimum clearance and recovering acetylene from said gaseous products.

4. A method for producing acetylene which comprises introducing a gaseous mixture containing a hydrocarbon and oxygen into a reaction zone at an initial linear gas velocity not greater than the flame velocity of the gaseous mixture, subjecting said mixture to flame combustion in said zone, conveying said ignited gaseous mixture downwardly towards the locus of minimum clearance between the surfaces of two oppositely rotating cooled metallic cylinders revolving on substantially horizontal axes and disposed so as to provide at said locus a relatively small clearance therebetween, said flame combustion taking place in a vertical plane located in said locus of minimum clearance, whereby at least a portion of the heat of combustion is removed from the resulting gaseous products, conveying said partially cooled ignited gaseous mixture through said locus of minimum clearance at a linear velocity substantially above the respective flame velocity, withdrawing the resulting gaseous products from a zone below said locus oi minimum clearance,

and recovering acetylene from said gaseous products. 1

5. The method according to claim 4 wherein the carbon formed as a by-product of the incomplete combustion reaction and deposited on the surfaces of the rotating metallic cylinders is continuously removed therefrom so as to contact the inflowing ignited gaseous mixture with substantially clean metallic surfaces, thereby aiding the cooling of the flame and increasing the acetylene yield.

6. A method for producing acetylene which comprises introducing a gaseous mixture containing a hydrocarbon and oxygen into a reaction zone at an initial linear gas velocity not greater than the flame velocity of the gaseous mixture, subjecting said mixture to flame combustion in said zone, c'onveyingsaid ignited gaseous mixture downwardly towards and through the locus of minimum clearance between the surfaces of two oppositely rotating cooled metallic cylinders revolving on substantially horizontal axes and disposed so as to provide at said locus a relatively small clearance therebetween, said flame combustion taking place in a vertical plane located in said locus of minimum clearance, whereby the gaseous mixture subjected to flame combustion is'graduall impinged on said rotating metallic cylinders as it moves towards and through said locus of minimum clearance, cooling said gaseous mixture, while it passes between the revolving metallic cylinders, to a temperature below that of flame combustion whereby the resulting gaseous products after passage through said locus of minimum clearance are at a temperature below that of flame combustion, withdrawing said resulting gaseous products from azone below said locus of minimum clearance, and recovering acetylene from said said gaseous products.

7. A method for producing acetylene which comprises subjecting a gaseous mixture containing a hydrocarbon and oxygen to incomplete combustion in a reaction zone at the ignition temperature of the gaseous mixture, conveying said mixture while maintaining flame combustion downwardly towards the locus of minimum clearance between the surfaces of two oppositel rotating cooled metallic cylinders revolving on substantially horizontal axes and disposed so as to provide a relatively small clearance therebetween, said incomplete combustion taking place in a vertical plane located substantially midway between the axes of said cylinders, maintaining the linear velocity of the gaseous mixture, while it passes through the locus of minimum clearance, substantially above the respective flame velocity of the gaseous mixture, simultaneously cooling the gaseous mixture whereby the resulting gaseous products, after passage through said locus of minimum clearance, are at a temperature below that of flame combustion, continuously removing carbon deposited on the surfaces of said metallic cylinders thereby bringing the ignited gaseous mixture in the reaction zone into contact with substantially clean portions of the rotating metallic cylinders, thus aiding heat transfer from the hot gaseous mixture to the surfaces of the metallic cylinders, withdrawing the resulting gaseous products from a zone below the locus of minimum clearance between the metallic cylinders, and recovering acetylene from said gaseous products.

8. A method for producing acetylene which comprises subjecting a gaseous mixture containing a hydrocarbon and oxygen to incomplete combustion in a reaction zone at the ignition temperature of the gaseous mixture, conveying said mixture while maintaining flame combustion to-- wards the locus of minimum clearance between the surfaces of two oppositely rotating cooled metallic cylinders revolving on substantially horizontal axes and disposed so as to provide a relatively small clearance at said locus, said incomplete combustion taking place in a vertical plane located substantially midway between the axes of said cylinders, coolin said gaseous mixture, while it passes between the revolving metallic cylinders, to a temperature below that of flame combustion, whereby the resulting gaseous products after passage through said locus of minimum clearance are at a temperature below that of flame combustion, withdrawing the resulting gaseous products products from a, zone downstream of said locus of minimum clearance, and recovering acetylene from said gaseous products.

9. The method according to claim 8 wherein the linear gas velocityof the gaseous mixture while passing through the locus of minimum clearance between the revolving cylinders is maintained substantially above the respective I flame velocity of the gaseous mixture.

10. A method for producing acetylene which comprises subjecting a gaseous mixture containing a hydrocarbon and oxygen to incomplete combustion in a, reaction zone at the ignition temperature or the gaseous mixture, conveying said mixture while maintaining flame combustion towards the locus of minimum clearance between the surfaces of two oppositely rotating cooled metallic cylindrical 'drums revolving on substantially parallel axes and with a relatively small clearance between said drums at said locus of minimum clearance, said incomplete combus- 'tion taking place substantially solely in a plane extending through said small clearance between said drums, maintaining the linear velocity of the gaseous mixture, while it passes through said locus of minimum clearance, substantially above the respective flame velocity of the gaseous mixture, whereby the resulting gaseous products after passage through said locus of minimum clearance are at a temperature below that of flame combustion, withdrawing the resulting gaseous products from a zone downstream of said locus of minimum clearance, and recovering acetylene from said resulting gaseous products.

11. An apparatus for producing acetylene by the incomplete and controlled flame combustion of a gaseous mixture containing a hydrocarbon and oxygen, which comprises a casing, two horizontally disposed cylinders within said casing and extending substantially the length of the casing, said cylinders being arranged so as to provide a relatively small clearance therebetween, pipe communicating with each end of each of said cylinders and adapted to convey a cooling fluid therethrough, means communicating with said cylinders and adapted to revolve them in opposite directions to each other, a gasintroducing manifold disposed in the upper portion of the casing, extending the length thereof, arranged in the vertical plane extending through the opening between the cylinders and provided with openings for the exit of the gaseous mixture downwardly and substantially throughout the length of said manifold, and means in the lower portion of the casing adapted to remove the reaction products'therefrom.

12. An apparatus according to claim 11, where in scraping means are provided within the casing to remove carbon depositing on the surfaces of the rotating cylinder 13. An apparatus for producing acetylene by the incomplete and controlled flame combustion of a gaseous mixture containing a hydrocarbon and oxygen, which comprises a casing, two cylinders disposed within said casing extending substantially the length thereof, being disposed on substantially horizontal axes and arranged so as provide a relatively small clearance therebetween, means communicating with each of said cylinders and adapted to circulate a cooling fluid therethrough, means on said last-mentioned means adapted to revolve said cylinders so that the tops thereof move inward towards the locus of minimum clearance therebetween, gas-introduction means extending substantially the entire length of the casing, arranged in the upper portion of casing in the vertical plane extending through the opening between the cylinders and provided with openings for the exit of the gaseous mixture substantially throughout its length, and means in the lower portion of the casing adapted to remove the reaction products therefrom.

14. An apparatus for producing acetylene by the incomplete and controlled flame combustion of a gaseous mixture containing a. hydrocarbon and oxygen, which comprises a casing, two cylinders within said casing extending substantially the length of the casing, being disposed on substantially horizontal axes and arranged so as to provide a relatively small clearance therebetween, means attached to said cylinders and adapted to revolve them so that the tops thereof move inward and towards the locus of minimum clearance therebetween, gas-introduction means extending substantially the entire length of the casing, arranged in the upper portion of casing in the vertical plane extending through the opening between the cylinders and provided with openings for the exit of the gaseous mixture substantially throughout its length, and means in the lower portion of the casing adapted to remove the reaction products therefrom.

15. An apparatus for producing acetylene by the incomplete and controlled combustion of a gaseous mixture containing a hydrocarbon and oxygen, which comprises a casing, two oppositely revolving cylinders within said. casing, said cylinders extending substantially the length of the casing, being disposed on substantially horizontal axes and being arranged so as to provide l a relatively small clearance therebetween, gasintroduction means extending substantially the entire length of the casing, arranged in the upper portion of casing in the vertical plane extending through the opening between the cylinders and provided with openings for the exit of the gaseous mixture substantially throughout its 4 length, and means in the lower portion of the casing adaptedto remove the reaction products therefrom.

LEONARD GOLDSTEIN. JAN D. BUYS.- 

